Two-dimensional materials have garnered interest from the perspectives of physics, materials, and applied electronics owing to their outstanding physical and chemical properties. Advances in exfoliation and synthesis technologies have enabled preparation and electrical characterization of various atomically thin films of semiconductor transition metal dichalcogenides (TMDs). Their two-dimensional structures and electromagnetic spectra coupled to bandgaps in the visible region indicate their suitability for digital electronics and optoelectronics. To further expand the potential applications of these two-dimensional semiconductor materials, technologies capable of precisely controlling the electrical properties of the material are essential. Doping has been traditionally used to effectively change the electrical and electronic properties of materials through relatively simple processes. To change the electrical properties, substances that can donate or remove electrons are added. Doping of atomically thin two-dimensional semiconductor materials is similar to that used for silicon but has a slightly different mechanism. Three main methods with different characteristics and slightly different principles are generally used. This review presents an overview of various advanced doping techniques based on the substitutional, chemical, and charge transfer molecular doping strategies of graphene and TMDs, which are the representative 2D semiconductor materials.

Flexible artificial synapses are fabricated with a SIZO/ion gel hybrid structure forming a polyimide substrate.

The AI and IoT era requires software and hardware capable of efficiently processing massive amounts data quickly and at a low cost. However, there are bottlenecks in existing Von Neumann structures, including the difference in the operating speed of current-generation DRAM and Flash memory systems, the large voltage required to erase the charge of nonvolatile memory cells, and the limitations of scaled-down systems. Ferroelectric materials are one exciting means of breaking away from this structure, as Hf-based ferroelectric materials have a low operating voltage, excellent data retention qualities, and show fast switching speed, and can be used as non-volatile memory (NVM) if polarization characteristics are utilized. Moreover, adjusting their conductance enables diverse computing architectures, such as neuromorphic computing with analog characteristics or ‘logic-in-memory’ computing with digital characteristics, through high integration. Several types of ferroelectric memories, including two-terminal-based FTJs, three-terminal-based FeFETs using electric field effect, and FeRAMs using ferroelectric materials as capacitors, are currently being studied. In this review paper, we include these devices, as well as a Fe-diode with high on/off ratio properties, which has a similar structure to the FTJs but operate with the Schottky barrier modulation. After reviewing the operating principles and features of each structure, we conclude with a summary of recent applications that have incorporated them.

In this paper, a p-type inverted-T FinFET (IT FinFET) has been optimally structured. Focus is made on analyzing the inferior characteristics reported from the previously fabricated IT FinFETs, and obtaining better performances through a novel structure. IT FinFET has a higher layout efficiency and can thus provide larger drain current (I _D ) under the same dimension as that of a silicon-on-insulator (SOI) FinFET by securing the extended channels of ultrathin body (UTB) on the field region. We closely observe the leverages of fin width (W _fin ), UTB height (H _UTB ), and gate length (L _g ) on the operation characteristics using a 3-D technology computer-aided design simulation with quantum-mechanical models. W _fin below 10 nm is evaluated to be suitable for strong gate controllability.We first examine a critical H _UTB , beyond which a higher drive current is not obtained even with a greater channel width than that of FinFET. When H _UTB = 3 and 10 nm, IT FinFET yields 13.3% and 142% of saturation current improvement compared with SOI FinFET under the same footprint. At extremely scaled L _g , although the immunity against short-channel effects is slightly weaker than that of SOI FinFET, optimally designed IT FinFET can produce a higher current and demonstrates shorter intrinsic delay times.

The advantageous role of 2D electron gas presence at the AlGaN/GaN interface attracts huge interest in the field of GaN‐based ultraviolet photodetector technology. However, the presence of high dark current deteriorates the photodetector performance by diminishing several figures of merit. In this work, enhanced figures of merit are demonstrated by employing interdigitated p‐GaN finger structure on the top of the AlGaN/GaN heterostructure. The commonly present high dark current in p‐GaN/AlGaN/GaN planar photodetector is largely reduced (from ≈µA to few pA) by etching the p‐GaN, excluding the electrode region. Furthermore, by using a graphene transparent electrode along with the p‐GaN interdigitated fingers on AlGaN/GaN heterostructure, ultraviolet photodetectors with superior sensitivity (3.55 × 10⁶) and ultrahigh detectivity (1.91 × 10¹⁴ cm Hz^1/2 W⁻¹) are realized at 360 nm. A comparison of graphene/p‐GaN and Ni/Au/p‐GaN interdigitated fingers and planar p‐GaN (with interdigitated graphene contacts) all on AlGaN/GaN heterostructure allows to understand the dominant roles of electrode transparency and the heterojunction structure. The simple and high electron mobility transistor‐compatible fabrication process of UV detectors provides a unique application in the field of UV sensing technology.